9,242 research outputs found
Effects of Hybrid Poplar (Salicaceae) Clone and Phenology on Gypsy Moth (Lepidoptera: Lymantriidae) Performance in Wisconsin
Gypsy moth (Lymantria dispar) developmental interactions with two hybrid Populus species clones were studied in laboratory trials. Significant differences in larval performance were found between clones and within the same clone at different phenological states. No larvae were able to complete development on clone NM6. All gypsy moth larvae feeding on clone NC5271 survived when leafflush was synchronized with gypsy moth eclosion in early May. However, neonates feeding on NC5271 foliage in July experienced in- creased mortality. Weights of surviving gypsy moth larvae feeding on NC5271 foliage in May versus July were not significantly different
Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 2: Data analysis
Assessing the performance of a MOD-OA horizontal axis wind turbine connected to an isolated diesel utility, a comprehensive data measurement program was conducted on the Block Island Power Company installation on Block Island, Rhode Island. The detailed results of that program focusing on three principal areas of (1) fuel displacement (savings), (2) dynamic interaction between the diesel utility and the wind turbine, (3) effects of three models of wind turbine reactive power control are presented. The approximate two month duration of the data acquisition program conducted in the winter months (February into April 1982) revealed performance during periods of highest wind energy penetration and hence severity of operation. Even under such conditions fuel savings were significant resulting in a fuel reduction of 6.7% while the MOD-OA was generating 10.7% of the total electrical energy. Also, electrical disturbance and interactive effects were of an acceptable level
Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1: Executive summary
Primary results are summarized for a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The MOD-OA installation considered was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program and was characterized by the highest wind energy penetration levels of four sites. The study analyses address: fuel displacement, dynamic interaction, and three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted on Block Island, Rhode Island
Self-organization and Mechanical Properties of Active Filament Bundles
A phenomenological description for active bundles of polar filaments is
presented. The activity of the bundle results from crosslinks, that induce
relative displacements between the aligned filaments. Our generic description
is based on momentum conservation within the bundle. By specifying the internal
forces, a simple minimal model for the bundle dynamics is obtained, capturing
generic dynamic behaviors. In particular, contracted states as well as solitary
and oscillatory waves appear through dynamic instabilities. The introduction of
filament adhesion leads to self-organized persistent filament transport.
Furthermore, calculating the tension, homogeneous bundles are shown to be able
to actively contract and to perform work against external forces. Our
description is motivated by dynamic phenomena in the cytoskeleton and could
apply to stress-fibers and self-organization phenomena during cell-locomotion.Comment: 19 pages, 10 figure
The non-Gaussian tail of cosmic-shear statistics
Due to gravitational instability, an initially Gaussian density field
develops non-Gaussian features as the Universe evolves. The most prominent
non-Gaussian features are massive haloes, visible as clusters of galaxies. The
distortion of high-redshift galaxy images due to the tidal gravitational field
of the large-scale matter distribution, called cosmic shear, can be used to
investigate the statistical properties of the LSS. In particular, non-Gaussian
properties of the LSS will lead to a non-Gaussian distribution of cosmic-shear
statistics. The aperture mass () statistics, recently introduced as
a measure for cosmic shear, is particularly well suited for measuring these
non-Gaussian properties. In this paper we calculate the highly non-Gaussian
tail of the aperture mass probability distribution, assuming Press-Schechter
theory for the halo abundance and the `universal' density profile of haloes as
obtained from numerical simulations. We find that for values of
much larger than its dispersion, this probability distribution is closely
approximated by an exponential, rather than a Gaussian. We determine the
amplitude and shape of this exponential for various cosmological models and
aperture sizes, and show that wide-field imaging surveys can be used to
distinguish between some of the currently most popular cosmogonies. Our study
here is complementary to earlier cosmic-shear investigations which focussed
more on two-point statistical properties.Comment: 9 pages, 5 figures, submitted to MNRA
Effective operators from exact many-body renormalization
We construct effective two-body Hamiltonians and E2 operators for the p-shell
by performing ab initio no-core shell model (NCSM) calculations
for A=5 and A=6 nuclei and explicitly projecting the many-body Hamiltonians and
E2 operator onto the space. We then separate the effective E2
operator into one-body and two-body contributions employing the two-body
valence cluster approximation. We analyze the convergence of proton and neutron
valence one-body contributions with increasing model space size and explore the
role of valence two-body contributions. We show that the constructed effective
E2 operator can be parametrized in terms of one-body effective charges giving a
good estimate of the NCSM result for heavier p-shell nuclei.Comment: 9 pages, 8 figure
Ab-initio shell model with a core
We construct effective 2- and 3-body Hamiltonians for the p-shell by
performing 12\hbar\Omega ab initio no-core shell model (NCSM) calculations for
A=6 and 7 nuclei and explicitly projecting the many-body Hamiltonians onto the
0\hbar\Omega space. We then separate these effective Hamiltonians into 0-, 1-
and 2-body contributions (also 3-body for A=7) and analyze the systematic
behavior of these different parts as a function of the mass number A and size
of the NCSM basis space. The role of effective 3- and higher-body interactions
for A>6 is investigated and discussed
On the particle paths and the stagnation points in small-amplitude deep-water waves
In order to obtain quite precise information about the shape of the particle
paths below small-amplitude gravity waves travelling on irrotational deep
water, analytic solutions of the nonlinear differential equation system
describing the particle motion are provided. All these solutions are not closed
curves. Some particle trajectories are peakon-like, others can be expressed
with the aid of the Jacobi elliptic functions or with the aid of the
hyperelliptic functions. Remarks on the stagnation points of the
small-amplitude irrotational deep-water waves are also made.Comment: to appear in J. Math. Fluid Mech. arXiv admin note: text overlap with
arXiv:1106.382
Anisotropy and XKS-splitting from geodynamic models of double subduction: Testing the limits of interpretation
In this study, we develop three-dimensional geodynamic models to predict XKS-splitting for double subduction scenarios characterized by two outward dipping slabs. These models are highly relevant in various realistic settings, such as the central Mediterranean. We focus on the analysis of XKS-splitting, a key geophysical observable used to infer seismic anisotropy and mantle flow patterns predicted from these geodynamic models. Our geodynamic models simulate the concurrent subduction of two identical oceanic plates which are separated by a continental plate. The variation of the separating plate strength, cause a transition from a retreating to a stationary trench. The models provide detailed insights into the temporal evolution of mantle flow patterns, especially the amount of trench parallel flow, induced by these double subduction scenarios. In a second step, we use the well-known D-Rex model (Kaminski et al., 2004) to efficiently estimate the CPO development in response to plastic deformation produced by mantle flow. Based on the results of the D-Rex model, which includes the full elastic tensor of a deformed multiphase polycrystalline mantle aggregate within the three-dimensional model, we obtain synthetic apparent splitting parameters at receivers placed at the surface by applying multiple-layer anisotropic waveform modeling. Employing analytical techniques, we show the ambiguous nature of apparent splitting parameters, as already suggested by previous studies based on numerical modeling. In the light of the results, we postulate that a meaningful inversion, based on the commonly applied 2-layer anisotropic model, requires additional constraints on fast-axis orientation or strength of anisotropy (delay time). Finally, we show that constraints from our texture simulations (i.e., the integrated delay time) can be used to achieve unique 2-layer models that perfectly fit the synthetic observables. Such models could serve as reference for the interpretation of the observations. Our study highlights the necessity of combining geodynamic modeling and XKS-splitting analysis to shed light on complex upper mantle flow patterns such as those that might occur around subduction zones
Annotated Bibliography of Fire Literature Relative to Northern Grasslands in South-Central Canada and North-Central United States
This publication provides a condensed reference of fire literature for those with an interest in fire ecology
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